1. Field of the Invention
The present invention relates to a burner for operating a heat generator.
2. Discussion of Background
EP-0 780 629 A2 has disclosed a burner which consists of a swirl generator on the incident-flow side, the flow formed herein being passed over smoothly into a mixing section. This is done with the aid of a flow geometry, which is formed at the start of the mixing section for this purpose and consists of transition passages which cover sectors of the end face of the mixing section, in accordance with the number of acting sectional bodies of the swirl generator, and run helically in the direction of flow. On the outflow side of these transition passages, the mixing section has a number of prefilming bores, which ensure that the flow velocity along the tube wall is increased. This is then followed by a combustion chamber, the transition between the mixing section and the combustion chamber being formed by a jump in cross section, in the plane of which a backflow zone or backflow bubble forms. The swirl intensity in the swirl generator is therefore selected in such a way that the breakdown of the vortex does not take place inside the mixing section but further downstream, as explained above, in the region of the jump in cross section.
Although this burner, compared with those from the prior art, guarantees a significant improvement with regard to intensification of the flame stability, lower pollutant emissions, lower pulsations, complete burn-out, large operating range, good cross-ignition between the various burners, compact type of construction, improved mixing, etc., it has been found that the increasing demands placed on burner technology may give rise to problems with regard to adequate premixing between the fuel and the combustion air, with the result that the pollutant emissions cannot always be minimized to the desired extent. In this respect, in order to counteract this, it would be necessary for the distance between the fuel injection location and the flame front to be very long, which in the case of a burner for operating a heat generator is not possible for spatial reasons and operating considerations.